29.4.11
UNIGATE fieldbus gateway for ProfibusDP V. 4.7
17
Deutschmann Automation GmbH & Co. KG
Mode of operation of the system
6
Mode of operation of the system
6.1
General explanation
Communication can be split into seven layers, Layer 1 to Layer 7, in accordance with the
ISO/OSI model.
The Deutschmann Automation gateways convert Layers 1 and 2 of the customized bus system
(RS485 / RS232) to the corresponding fieldbus system. Layers 3 to 6 are blank, and Layer 7 is
forwarded transparently on the RS-standard gateways. However, customized adaptations are
also possible here (e.g. adaptations to existing profiles of the fieldbus systems).
The gateway can be configured through the software WINGATE
®
that is also supplied (see also
6.2
Interfaces
The gateway features the RS232 and RS485 interfaces. Switchover is performed by means of a
slide switch accessible for the customer. The Profibus gateway thus allows access to all devices
connected to the RS485 bus via one single Profibus address resp. access to the device con-
nected to the RS232 interface.
6.3
Data exchange
The Profibus Master sends the output data cyclically to the gateway. The data received from the
Master is sent in the gateway to the external device in accordance with the selected protocol.
The external device responds in accordance with the protocol conventions.
The data received from the external device is written by the gateway into the internal RAM of the
SPC3. The updated data is then transferred on the next poll cycle with the gateway.
At the UNIGATE RS the data exchange via the RS interface can be programmed as follows:
•
Cyclic
•
Only if input data changes
•
Only if trigger byte changes
All data is transferred consistently by the gateway in both directions. The maximum data length
of consistent data must be noted in the case of data exchange between Master and CPU. This is
generally dependent on the Master interface connection and the CPU used.
Structure of the data:
Trigger byte and length byte are contained only if configured accordingly.
At UNIGATE SC all data that is transfered in dependence on the downloaded Script.
6.4
Possible data lengths
The table below shows the maximum transferable data:
Trigger byte See "The trigger byte - only at UNIGATE RS", Chapter 6.6‚ on page 18
Length byte See "The length byte - only at UNIGATE RS", Chapter 6.7‚ on page 18
User data
Input data
max. 244 bytes
Variable: maximum value in this case
Output data
max. 244 bytes
Variable: maximum value in this case
Parameters 8
bytes
No user parameters
Configuration data
max. 16 bytes
Dependent on configuration
Diagnosis
max. 8 bytes
1 user diagnostic bit = error code
Summary of Contents for UNIGATE RS232/422
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